Interventional radiology Venous interventions
Dilatation and stent placements for venous strictures are increasingly used for malignant and benign stenoses. For most venous narrowings, particularly those caused by tumor compression or fibrosing processes (superior and inferior vena cava syndrome), postoperative scarring or after recanalization of thrombotic occlusions, PTA alone is usually in sufficient and additional stenting has proved to give excellent long-term results (Fig. 6). In these conditions stenting is the method of choice. For outflow stenoses of hemodialysis fistula PTA remains the first approach with stenting reserved for recurrences or recoiling lesions.
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Figure 6.
Patient with superior V cava syndrome from mediastinal metastases due to bronchogenic carcinoma.
A) Bilateral arm phlebography shows severe stenoses of upper superior V cava and also some narrowing of the right brachioephalic vein. Note numerous collaterals and drainage via the azygous vein (arrows).
B) Follow-up phlebography 13 months after implantation of a 16 mm Wallstent reaching from the right brachiocephalic vein to the superior V cava. There is good antegrade drainage to right atrium. Note that the left brachiocephalic vein remains patent and empties through the mesh of the Wallstent. The patient survived without signs of venous obstruction for 18 months.
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Figure 7.
Patient with recurrent pulmonary emboli in spite of anticoagulation.
A) V. cavagram to measure the diameter of the V. cava and mark the level of the renal veins (arrows).
B) V. cavagram following percutaneous placement of titanium Greenfield filter shows good filter position. Arrows mark inflow of renal veins.
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Obliteration of spermatic veins for symptomatic varicoceles and infertility today is a standard alternative to surgical ligation. After selective catheterisation of the testicular vein embolization may be achieved with coils, detachable balloons or sclerosing agents on an outpatient basis.
Inferior vena cava filters were introduced in the late 60s and early 70s as a protection from recurrent pulmonary emboli despite anticoagulation or for patients with contraindications to anticoagulation. Various types of filters for percutaneous introduction have been developed over the last few years and some of these have proved a relatively safe and effective means of preventing pulmonary embolism. Great care should be taken during patient selection and the choice of the filter device should be based on the operator's experience (Fig. 7).
Retrieval of lost foreign bodies, mainly severed central venous catheters from the superior vena cava can be performed by a percutaneous transvenous approach. Retrieval from the vena cava, the right heart and even the pulmonary arteries by way of wires, snares and loops or hook-shaped catheters has a high success rate. These foreign bodies should be retrieved as early as possible before fixation by overgrowth of endothelium has occurred.
Christoph Zollikofer